Current technology requires either catalytically dewaxed, wax isomerate based Group III basestocks, or polyalphaolefins (PAOs) as the primary basestock to achieve certain requirements set by organizations such as ACEA (Association des Constructeurs d' Automobiles), ATIEL (Association Technique de L'Industrie Europeane des Lubrifiants), API (American Petroleum Institute), ILSAC (International Lubricant Standardization and Approval Committee), ASTM (American Society of Testing and Materials), EOLCS (Engine Oil Licensing and Certification System), SAE (Society of Automotive Engineers) for applications requiring excellent low temperature properties as well as high temperature stability. An example is SAE Grade 0W multi-grade engine oils and ILSAC GF-4 specifications. There is currently a limited supply of both of these relatively expensive basestocks and development of alternatives is needed to meet growing demand. Technology to enable the use of more petroleum-derived basestocks in such formulations is highly sought-after.
U.S. Pat. No. 5,693,598 describes a low viscosity oil having a kinematic viscosity of up to about 4 cSt at 100° C. and a composition having antiwear properties and comprising said oil. The feed comprises from about 60 to about 90% C12.
U.S. Pat. No. 5,789,355 relates to SAE Grade 5W and higher multigrade oils including a basestock and a detergent inhibitor package. The basestock is selected from API Groups I and II. The detergent inhibitor package includes an ashless dispersant derived from an ethylene alphaolefin (EAO).
U.S. Pat. No. 6,303,548 is directed to a base oil for an SAE Grade 0W40 lubricant composition comprising a PAO and a synthetic ester lubricant.
U.S. Pat. No. 6,824,671 describes a mixture of about 50 to 80 wt. % 1-decene and about 20 to 50 wt. % 1-dodecene are co-oligomerized in two continuous stirred-tank reactors in series using BF3 with an ethanol:ethyl acetate promoter. Monomers and dimers are taken overhead and the bottoms product is hydrogenated to saturate the trimers/oligomers to create a 5 cSt PAO. This product is further distilled and the distillation cuts blended to produce a 4 cSt PAO containing mostly trimers and tetramers, and a 6 cSt PAO containing trimers, tetramers, and pentamers. The lubricants thus obtained are characterized by a Noack volatility of about 4% to 12%, a pour point of about −40° C. to −65° C. See also copending U.S. application Ser. No. 10/959,544.
U.S. Patent Application 2004/0033908 describes a fully-formulated lubricant comprising PAOs, including a PAO prepared from an oligomerization process comprising contacting an alphaolefin feed with a BF3 catalyst and a promoter (or cocatalyst) system including an alcohol and an ester.
The use of Group III lube basestocks blended with Group II basestocks is currently available commercially to make 5W-XX engine oils (where XX can be 10, 20, 30, 40). However, as far as the present inventors are aware, heretofore no 0W-XX engine oil has been formulated using a Group II basestock.
The present inventors have surprisingly discovered that this same new low viscosity PAO allows for blending of a high percentage of Group II basestock to achieve an engine oil capable of meeting 0W-XX requirements.